Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1998-12-08
2001-05-15
Paladini, Albert W. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S256000, C361S777000
Reexamination Certificate
active
06232560
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention is related to an arrangement of printed circuit traces, and more particularly to an arrangement of printed circuit traces which ensures proper signal transmission by eliminating cross talk between adjacent signal traces.
2. The Prior Art
Printed circuit boards are essential elements of any computer system for mounting electrical components thereon and providing an efficient method of signal transmission between the components through signal traces formed therein. Flexible printed circuits are also becoming increasingly popular due to the efficient use of space provided thereby. As the trend of the computer industry continues toward miniaturization, the signal traces of printed circuits are being formed at increasingly higher densities. Such close proximity results in cross talk between adjacent signal traces which adversely affects signal transmission.
A conventional arrangement of printed circuit traces is shown in
FIG. 5. A
ground plane
25
is formed on a bottom surface of a substrate
30
and a plurality of signal traces
10
are formed on a top surface thereof. Since the signal traces
10
are formed adjacent to each other near one surface of the substrate, cross talk therebetween and, subsequently, poor signal transmission are inevitable. In addition, control of the effective impedance of the signal traces
10
and ground plane
25
becomes complicated since the only variable design parameters are the depth and width of the signal traces
10
. An increase in the width of the signal traces
10
would result in more cross talk therebetween, and an increase in the height of the signal traces
10
would increase the occupied space of a circuit board in which the signal traces
10
are formed.
FIG. 6
shows a conventional four layer printed circuit arrangement used in high speed signal transmission applications. A pair of internal planes
25
,
45
serve as a means for conducting ground and power signals, respectively, and a substrate
30
is provided therebetween and on outer surfaces thereof. Signal traces
10
are formed on near outer surfaces of the substrate
30
. Cross talk between adjacent signal traces
10
is reduced by such an arrangement but the cost of manufacture is greatly increased. Furthermore, control of the effective inductance between power and ground becomes complicated due to the power and ground planes
25
,
45
not having variable parameters.
Therefore, an improved arrangement of printed circuit traces is required which can overcome the disadvantages of the prior art.
SUMMARY OF THE INVENTION
Accordingly, an objective of the present invention is to provide an arrangement of printed circuit traces having a high density of signal traces.
Another objective of the present invention is to provide an arrangement of printed circuit traces whereby cross talk is effectively eliminated between adjacent signal traces.
A further objective is to provide an arrangement of printed circuit traces having variables for controlling effective impedance and inductance between different types of circuit traces.
Yet another objective of the present invention is to provide an arrangement of printed circuit traces having an increased number of signal traces.
Yet a further objective of the present invention is to provide an arrangement of printed circuit traces which facilitates the cost efficient manufacture of a printed circuit board or a flexible printed circuit.
To fulfill the above objectives, an arrangement of printed circuit traces in accordance with an aspect of the present invention comprises a plurality of signal and ground traces alternately arranged on both surfaces of a substrate whereby no two signal traces are adjacent to each other and a signal trace on one surface is aligned with a ground trace on the opposite surface.
According to another aspect of the present invention the ground traces on one surface of the substrate are replaced with power traces for high speed signal transmission applications.
In accordance with a third aspect of the present invention, a pair of signal traces are provided between adjacent power traces on one surface of a substrate and between adjacent ground traces on an opposite surface of the substrate. Each signal trace is
15
formed closer to the adjacent power trace or ground trace than the adjacent signal trace. The width of each power trace and ground trace is larger than the distance between outer extremes of each pair of signal traces.
These and additional objectives, features, and advantages of the present invention will become apparent after reading the following detailed description of the preferred embodiments of the invention taken in conjunction with the appended drawing figures.
REFERENCES:
patent: 4707671 (1987-11-01), Suzuki et al.
patent: 5764489 (1998-06-01), Leigh et al.
Chung Wei Te
Hon Hai - Precision Ind. Co., Ltd.
Paladini Albert W.
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